Applications

Selective differential medium for the isolation of Listeria monocytogenes from food, clinical and environmental specimens

General

Palcam agar is a selective differential medium for the isolation of Listeria monocytogenes from food, clinical and environmental specimens.The Columbia peptone mix and starch provide the required carbon, nitrogen and vitamins.

Glucose is a fermentable carbohydrate. Differentiation of Listeria spp. from enterococci and staphylococci occurs through aesculin hydrolysis and mannitol fermentation. Listeria monocytogenes will hydrolyse aesculin and the associated reaction with the ferric ammonium citrate gives rise to a brown/black precipitate around the colonies.

Listeria spp. do not however ferment mannitol. Mannitol fermentation is seen through a colour change of the colony or the area around the colony from red to yellow due to the production of acidic end products.

Phenol red is the pH indicator in the medium. Lithium chloride is included to inhibit enterococci. The associated Palcam selective supplement, LS0038, contains polymyxin B, acriflavine and ceftazidime to inhibit other Gram-positive and Gram-negative organisms that may be present in specimens.

Specification

• Shelf Life (days): 1095 days
• Storage Temp (°C): 10-30°C
• Dehydrated Medium Appearance: Fine Powder
• Prepared Medium Appearance: Firm Gel
• Dehydrated Medium Colour: Beige
• Prepared Medium Colour: Red
• Dehydrated PH: 7.2 ± 0.2
• Prepared PH: 7.2 ± 0.2
• Recommended Incubation: Aerobically at 37°C for 48 hours
• Formula g/L
• Columbia Peptone Mix: 23.0
• Sodium Chloride: 5.0
• Corn Starch: 1.0
• Glucose: 0.5
• Mannitol: 10.0
• Aesculin: 0.8
• Lithium Chloride: 15.0
• Ferric ammonium citrate: 0.5
• Phenol Red: 0.08
• Agar: 12.0
• Total: 68.0